Writing instruments of the ball tip type



H. R. FEHLING 2,708,903 WRITING INSTRUMENTS OF THEBALL TIP TYPE Filed June 25, 1950 F/G /a.

Attorney S* May 24, 1955 United States Patent() WRITING INSTRUMENTS OF THE BALL TIP TYPE Hans Reinhard Fehling, London, England, assignor to Campania Uruguaya de Fomento Industrial S. A., Montevideo, Uruguay, South America Application June 23, 1950, Serial No. 169,849

4 Claims. (Cl. 1Z0-42.4)

This invention concerns reservoir writing instruments of the ball-tip type wherein the writing extremity comprises a writing ball yhoused in and partly protruding from a socket or housing, which ball is supplied with ink from a reservoir by means of a small duct or passage having communication with the base of the socket or to atmosphere at its rear end. An ink vein extends through the reservoir to the ball and the meniscus which is formed at the rear end of this vein, at the interface between the ink, the air, and the interior walls of the reservoir, is subjected to atmospheric pressure.

Writing instruments having such reservoirs are eminently satisfactory in operation and do not leak, but the quantity of ink contained by the reservoir is limited and the refilling of the reservoir is an operation which cannot be carried out by the user or by any other party not provided with the appropriate apparatus. One object of the present invention is the provision of a writing instrument of the type specified in which the reservoir contains a greater volume of ink than do the reservoirs of instruments according to the two patents above referred to, and in which the reservoir can be refilled by the user and/or by the use of the most simple form of apparatus.

With this and other objects in View the invention provides a reservoir writing instrument of the type specified,

wherein the reservoir is closed except at its mouth or juncture with the writing extremity, and has at least the area of its walls of such a character as to be capable of responding to or adapting itself to a diminution in the volume of the reservoir contents and thereby adapting the cubical capacity of the reservoir to variations in said volume, which reservoir has a filling orifice which is normally closed to prevent escape of ink but through which ink may be introduced into the reservoir when required. Preferably, the reservoir comprises a flexible sac.

It will therefore be appreciated that the instrument may be used until the reservoir is at least partly exhausted, the flexible reservoir wall permitting the reservoir to adapt its capacity to the diminishing volume of ink and, at the appropriate stage, a fresh charge of ink may be introduced into the reservoir through the filling orifice. This fresh charge may be forced in under pressure such as that supplied by gravity or by a simple form of pump, the reservoir walls thereupon responding to the increase in volume so as to adapt the reservoir capacity to the increase. This deformation may be imposed on the reservoir walls by extraneous means or may result from the natural elasticity of the walls.

The filling orifice may be the mouth of the reservoir, in which case the reservoir and writing extremity must be constructed to be readily detachable from each other.

In the accompanying drawings:

Figures 1A and 1B collectively show, in longitudinal section, one form of writing instrument according to this invention; Figure 1A showing the writing end or front end, and Figure 1B showing the rear end of the instrument.

Referring to Figures 1A and 1B, the writing instrument therein illustrated comprises an outer barrel or casing 1 to the front end of which there is secured an adaptor 2. This adaptor serves to form the end of a reservoir 3, and also to unite the casing 1 and the reservoir to a writing extremity 4 screwed into the outer end of the adaptor. ln the adaptor is a small-bore feed duct 5 which leads from the interior of the reservoir 3 to a feed duct 6 in the writing extremity 4. At the junction betewen the bores 5 and 6 there is a restricted orifice 5a which is preferably between 0.5 and 1 mm. in diameter.

The writing extremity 4 is equipped with a writing ball 7 rotatably mounted in a socket or housing and for further particulars thereof reference is to be made to the specifications of British Letters Patent No. 564,172, L. l. Biro, and No. 609,817, H. G. Martin.

The res-ervoir 3 further includes a flexible tubular ink sac 8, one end of which is fitted to a union 9 formed on the rear end of the adaptor 2. The other end of the sac 8 may be closed by being fitted on to a plug member 10 which is secured within the casing 1, for example by means of screw 11. This plug has a larger part to fit within the inner bore of the casing 1 and a smaller part to receive the end of the tube 8.

The sac 8 may be flaccid, see Letters Patent No. 602,101, L. J. Biro, or it may be such as to be distended when filled and to exert a slight pressure on its contents (this pressure being such that the ink pressure is not great-er than the capillary pressure at the ball), in accordance with British Letters Patent No. 633,821, H. G. Martin, the tube being so constructed and of such a material that it tends to collapse to a flattened form. The tube may be made of synthetic rubber or an oil-resistant plastic of similar mechanical characteristics to rubber.

As the ink in the reservoir is used up in writing, the sac 8 gradually approaches its attened form and so adapts its cubical capacity to the diminishing volume of ink. In order to permit of this alteration in shape and capacity of the sac 8, the casing 1 should be vented, a suitable air vent being indicated at 12 in Figure 1B.

It will be appreciated that such a reservoir as that described may be constructed so as to contain a considerable volume of ink and so to give a long writing life. It is immaterial that in many instances the instrument will not continue to write until the reservoir is completely exhausted. Indeed this is an advantage for it ensures that the ducts 5 and 6 cannot be written dry, and therefore, when the reservoir is refilled (as hereinafter described) the instrument is in condition to resume writing immediately, whereas were the ducts 5 and 6 written dry, ink would have to be caused to fill them before the instrument could be in condition to write. It may however be explained at this point that the instrument will cease to write when the ink within the reservoir attains a negative pressure which overcomes the capillary pressure at the ball.

The reservoir is refilled through the filling valve shown in Figure 1B. Removal of the cap 13, which may be an integral part of casing 1, or may be detachably connected to its end, exposes the protruding nozzle-like end of a filling tube 14 which extends through the plug 10 into the interior of the sac 11, where its inner protruding end 141 is covered by a closed-ended resilient displaceably secured tube 15. The tube 15 is xedly attached to the end 141 of the tube, and has a portion freely encircling inlet holes 16 formed in the walls of said end 141. This arrangement therefore constitutes a non-return valve in that, whereas the tube 15 prevents flow of ink from the interior of the reservoir outwards along tube 14, it permits ink to be forced along tube 14 and through the holes 16. The tube 15 is preferably made of synthetic rubber.

The holes 16 should not be less than 1 min. in diameter. The bore of tube 14 is of capillary size, which for the purpose of the present specification, is defined as being such that when the top end of the tube is closed and an uninterrupted ink column extends from this closed end towards the open end, a stable meniscus is formed at the end of this column at the interface between the ink, the air, and the interior surface of the tube, and the ink will not run out of the tube under the effect of gravity when the tube is held in such an attitude that the closed end is higher than the open end. The said bore should not be less than, and is preferably about, l mm. in diameter.

Since by virtue of its size and of the closure of its inner end by valve tube 15, the tube 14 will always remain full of ink, it follows that if the filling orifice at that end of its which is exposed by the removal of the cap 13 has ink forced into it by means of a refilling appliance, ink is ejected immediately into the interior of the reservoir 3, without the ingress of air.

The refilling device may be in the form of a compressible ink cartridge resembling a tooth-paste tube and hav ing means for connection with the filling tube 14.

A suitable ink forms the subject of British Letters Patent No. 621,847, H. G. Martin.

While a preferred embodiment of my invention has been described and illustrated, it is to be understood that modifcations as to form, arrangement of parts, and use of material may be made without departing from the scope and spirit of my invention as claimed herein.

I claim:

l. A writing instrument comprising a tubular outer casing, an adaptor secured to one end of the casing and having a part of reduced diameter within the casing, a ball point writing extremity on the outer end of the adaptor, a plug within said casing at its other end, fixed axially therein and also having a part of reduced diameter within the casing, a resiliently collapsible, flexible tubular reservoir secured on said reduced parts of the adaptor and plug, a feed conduit in the adaptor leading from the reservoir to the ball point, a filling tube passing through said plug into the reservoir, a one-way inlet valve on said tube within the reservoir, and a cap detachably secured to the end of the holder remote from the writing head, for enclosing the outer end of said filling tube.

2. A writing instrument according to claim 1 wherein the tubular reservoir is of fiattened form when empty, and wherein the feed tube to the reservoir protrudes outwardly from the said plug and has its protruding part enclosed by said cap.

3. A writing instrument according to claim 1, wherein the feed tube within the reservoir is closed at its inner end but has radial openings and wherein a flexible valve sleeve is displaceably secured on such tube so as to cover said openings freely to constitute said one-way valve.

4. ln a reservoir writing instrument of the ball point type comprising a tubular outer casing, a ball point writing extremity at one end thereof, a closed collapsible reservoir in the casing for containing ink, and a feed conduit leading from the reservoir to the ball point; the combination of a filling tube, of capillary size, having an outlet end protruding into the reservoir, and an inlet valve normally sealing said outlet end but yieldable to permit ink to be injected through the tube into the reservoir, which valve consists of a resilient sleeve surrounding and normally sealing said outlet end but capable of yielding to permit the ink injection.

References Cited in the file of this patent UNITED STATES PATENTS 1,864,050 Myers June 2l, 1932 2,099,891 Iohannesson Nov. 23, 1937 2,107,700 Haas Feb. 8, 1938 2,249,961 Kalman July 22, 1941 2,408,256 Florman Sept. 24, 1946 2,444,003 Chesler June 22, 1948 2,506,035 Parker May 2, 1950 

